Various arrangements have heretofore been provided and are in use for endeavoring to shear or sever elongated objects such as tubular members or cable which extend through a blowout preventer and then attempting to block or seal off communication through the blowout preventer after the tubular object has been sheared. Some of such devices include shear arrangements which are generally rectangularly in configuration but the configuration or arrangement is such that it may collapse or crush the ends of the tubular member being severed, particularly where the member is thin walled. Also, the sealing arrangement employed with such shear blades is generally unsatisfactory in that it may not adequately and positively seal or block off communication through the preventer after the tubular members or other object has been severed.
When pipe is severed or sheared in connection with drilling and production of oil and gas wells, it is common to provide a plurality of various types blowout preventers during the operation. For example, pipe rams of a blowout preventer are moved to closed position about the pipe or object to be sheared so that the well bore annulus therebeneath is sealed off. It is not uncommon for the pipe rams to be closed about the pipe immediately beneath a coupling or collar so that the pipe is then supported on the closed pipe rams after it has been sheared or severed.
A blowout preventer with shear rams is positioned in spaced relation above the preventer with pipe rams and it is actuated to shear the pipe and thereafter the portion of the sheared pipe above the shear rams is elevated by the draw works and drilling mast structure at the earth surface so that still another blowout preventer in spaced relation above the preventer with the shear rams may be actuated to close blind rams and prevent communication through the well bore above the sheared off section.
Thereafter the portion of the pipe or object above the shear rams is removed from the well bore and a suitable milling tool is lowered on a well string to engage the sheared end of the tubular member or object supported on the closed pipe rams to mill it off where it has been collapsed by the shear rams so that the pipe may be engaged by a fishing tool for recovery, or so that fluid may be communicated down through the exposed open end of the pipe to "kill" the well to inhibit "kicking" or a blowout in the well. In some situations pipe rams are provided above blind rams in the well bore which are closed against the well string during the milling operation.
The foregoing operation is expensive and time consuming.